Asphalt compositions having improved adhesion to aggregate

ABSTRACT

Asphalt compositions are provided having improved adhesion to aggregate, comprising an alkyl oxyalkylene amine and, optionally, an alkanolamine.

This is a division of application Ser. No. 353,271 filed Apr. 23, 1973,now U.S. Pat. No. 3,928,061.

Asphalt compositions have relatively poor adhesion to aggregate in thepresence of water. Aggregate is preferentially wetted by water, so thateven if the aggregate be dry at the time it is blended with the asphalt,in the course of time the penetration of water into the asphaltcomposition reaches the aggregate and then interferes with the bondbetween the aggregate and the asphalt, leading to separation of theasphalt from the aggregate, with resulting breakup of the composition.If, for example, it is in the form of a paving material, flaked pavementand potholes result.

The adhesion between asphalt and aggregate is greatly improved by theaddition of a cationic substance, such as an amine. The additiveincreases the hydrophobicity of the aggregate, so that the aggregatebecomes resistant to the penetration of water, as a result of whichwater seeping into the asphalt does not tend to destroy the bond betweenthe asphalt and the aggregate. If the aggregate is water-resistant,water does not prevent the formation of a good bond with the asphalt,even when the aggregate is wet. The result is an increased pavementlife.

The cationic additives used for this purpose are normally the primaryalkyl amines, such as lauryl amine, stearyl amine, and the alkylenediamines, particularly the alkyl-substituted alkylene diamines, such asN-stearyl-1,3-propylene diamine, are widely used for this purpose.However, these amines rapidly lose their activity when combined with theasphalt and stored at elevated temperatures. It has therefore beennecessary to combine the amine with the asphalt at the work site, wherethe asphalt is combined with the aggregate. It is, however, difficult tocombine the proper quantity of additive with the asphalt on site, andobtain a homogeneous mixture. There is also a certain danger in doing sosince the amines are toxic.

In order to avoid these difficulties, tertiary alkyl amines, aromaticamines, and heterocyclic amines have been used. These amines are morestable at elevated temperatures than primary amines, but they have alesser activity, and much larger amounts are required, for the samedegree of adhesion. Primary alkyl amines have also been condensed withethylene oxide, but the resulting adducts have the same limitations.

In accordance with the instant invention, it has now been determinedthat the adhesion of asphalt to aggregate can be appreciably improved bycombining with the asphalt an ether amine having the general formula:##STR1## wherein: R₁ is a hydrocarbon group having from about six toabout sixteen carbon atoms;

R₂, r₃, r₄ and R₅ are selected from the group consisting of hydrogen andalkyl radicals having from one to about two carbon atoms;

n₁ and n₂ are numbers within the range from one to about four;

x₁ and x₂ are numbers within the range from zero to about five, the sumof x₁ and x₂ being from one to five;

the total number of carbon atoms in each ##STR2## unit being from one toabout four.

An especially preferred class of ether amines in accordance with theinvention are those in which R₁ is an alkyl group having from eight toabout fourteen carbon atoms, the number of carbon atoms in each ##STR3##unit is two or three, x₁ is one, and x₂ is zero.

Exemplary R₁ substituents are hexyl, isohexyl, heptyl, octyl,2-ethylhexyl, isooctyl, nonyl, tertiary nonyl, decyl, dodecyl, tridecyl,myristyl, palmityl, hexenyl, heptenyl, octenyl, nonenyl, decenyl,dodecenyl, and tridecenyl.

Exemplary R₂, R₃, R₄ and R₅ alkyl substitutents are methyl, ethyl.

Exemplary ether amines in accordance with the invention areoctoxyethylamine, decoxyethylamine, dodecoxyethylamine,tetradecoxyethylamine, hexoxypropylamine, octoxypropylamine,nonoxypropylamine, decoxypropylamine, dodecoxypropylamine,tetradecoxypropylamine, palmityloxypropylamine, myristyloxypropylamine,hexyl dioxyethylene oxyethylamine, octyl trioxyethylene oxyethylamine,dodecyl tetraoxyethylene oxyethylamine, myristyl dioxyethyleneoxypropylamine, octyl tetraoxyethylene oxypropylamine, dodecyltetraoxyethylene oxypropylamine, octyl dioxypropylene oxypropylamine,decyl trioxypropylene oxyethylamine, tetradecyl tetraoxypropyleneoxypropylamine, octyl oxypropylene oxypropylamine, palmityltetraoxypropylene oxypropylamine, heptenyl oxypropylene oxypropylamine,decenyl dioxyethylene oxyethylamine, octenyl oxypropylene oxyethylamine,dodecenyl tetraoxypropylene oxypropylamine, octyloxybutyleneoxbutylamine, decyl trioxybutylene oxybutylamine, dodecyltetraoxybutylene oxyethylamine, palmityl dioxybutylene oxypropylamine,decyl tetraoxy propylene oxypropylamine, and dodecyloxy propyleneoxyethylamine.

The ether amine additives in accordance with the invention can beprepared from an adduct of an alcohol and the corresponding alkyleneglycol, such as an adduct of octyl alcohol and ethylene glycol,replacing the hydroxy group by halogen, preferably chlorine, and thenreacting the resulting halogen compound with ammonia. Alternatively, thealcohol or alkylene oxide adduct can be reacted with acrylonitrile, andthe resulting reaction product then hydrogenated. Direct amination ofthe alkylene oxide adduct in the presence of a suitable catalyst alsoresults in the ether amine. Other suitable methods include the reactionof the corresponding alcohol with formaldehyde and hydrochloric acid,the chlorine-containing ether compound then being reacted with ammonia.One also may employ alkene compounds having a suitable chain length,reacting them with a monoalkanolamine having from two to about fourcarbon atoms.

The ether amines in accordance with the invention have a superiorthermal stability in hot asphalt compositions. Their thermal stabilitycan be further improved by combining therewith an alkanolamine havingthe formula: ##STR4## wherein: R₆ and R₇ are selected from the groupconsisting of hydrogen and alkyl groups having from one to about twocarbon atoms;

n₃ is a number within the range from two to about four;

x₃ is a number within the range from one to about three;

the total number of carbon atoms in each ##STR5## unit being within therange from two to four.

The alkanolamine by itself has no noticeable effect upon the adhesion ofthe asphalt to aggregate. However, in combination with the ether amine,the adhesion of the asphalt to aggregate is greatly improved, suggestingthat there is a synergistic effect on the adhesion properties of theether amine. This effect cannot be explained at the present time, but itis suggested that possibly the alkanolamine in some way improved thestability of naphthenic acids present in the asphalt, which break downand/or inactivate the ether amine at elevated temperatures. The resultis an improved thermal stability of the asphalt composition, which tendsto retain good adhesion to aggregate even when held at elevatedtemperatures for long periods of time.

Exemplary R₆ and R₇ substituents in the alkanolamines are methyl, ethyl.

Exemplary alkanolamines are monoethanolamine, diethanolamine,triethanolamine, monoisopropanolamine, diisopropanolamine,triisopropanolamine, monoisobutanolamine, diisopropanolamine,triisopropanolamine, monoisobutanolamine, diisobutanolamine,triisobutanolamine, mono-n-propanolamine, di-n-propanolamine,tri-n-propanolamine, mono-n-butanolamine, di-n-butanolamine, andtri-n-butanolamine.

When the ether amine is used in combination with an alkanolamine, thetwo amines are preferably added together to the asphalt. If desired, theether amine and alkanol amine can be premixed, for addition to asphaltand aggregate at the work site.

When alkanolamine and ether amine are used together, the proportions ofalkanolamine and ether amine are in no way critical. The amount ofalkanolamine can be within the range from about 0 to about 90% byweight, preferably with the range from about 10% to about 70% by weight,of the ether amine. The upper limit is imposed by the diluting effect ofthe alkanolamine, which, when used alone, has no capability of improvingthe adhesion of asphalt to aggregate. Consequently, as the amount ofalkanolamine becomes greater, the adhesive effect of the diluted etheramine begins to be reduced. Therefore, the upper limit of alkanolamineis normally about 90% by weight of the ether amine. However, largeramounts of alkanolamine can be used if the ether amine has a strongeffect on the adhesion of asphalt to aggregate.

The amount of ether amine in the asphalt-aggregate composition dependsupon the adhesive effect desired. An amount of ether amine as low as0.1% gives an improved adhesion of asphalt to aggregate. As the amountof ether amine increases, the effect on the adhesion appears less, andamounts in excess of 5% weight of the asphalt do not appear to greatlyimprove adhesion to aggregate. Consequently, although amounts in excessof 5% can be used, such amounts are wasteful. Amounts in excess of 10%are not required. The preferred amount is within the range from about0.5% to about 4% by weight of the asphalt, within which range theoptimum effect on adhesion is observed.

The ether amines in accordance with the invention improve the adhesionto aggregate of any kind and form of asphalt composition.

The term "asphalt" as used herein is applied to an asphalt suitable fordirect use in highway work, roofing, and also for other purposes, andincludes asphalts brought to a consistency desired for particular use,either by distillation or by mixing or fluxing with a harder or a softerasphalt, as the case may be. The term "asphalt" also includes asphalticrocks, tars and pitches obtained in the distillation of coal or wood, orobtained from petroleum residues, cracking coal tars, or other types ofnatural asphalts. One type of asphalt is commonly known as "asphaltcement." Asphalt cement is a highly viscous product obtained byoxidizing or steamblowing a petroleum residue to increase itspenetration.

In using asphalt in road paving operations, three different proceduresare employed. In one procedure adapted for use of asphalt cement, theasphalt is heated until free-flowing, and then mixed directly with theaggregate, which may also be heated. In a second procedure, to enableapplication of asphalt to aggregate at room temperature, the asphalt isdissolved in a hydrocarbon solvent. Such compositions are known as"cut-back" asphalts. This method of asphalt application is expensive notonly because of the solvent but also because considerable time isrequired to remove the solvent once mixing has been completed.

In the third method, the asphalt is emulsified with water. The emulsioncan either be of the so-called oil-in-water type in which the asphalt isemulsified in the inner phase, or the emulsion can be of thewater-in-oil type in which water is in the inner phase. The particles ofasphalt in the emulsion range from about one to about twenty microns insize, and the emulsion is free-flowing at ordinary temperatures. Asphaltemulsions are generally made in three types: "RS" or rapid-setting type,"MS" or medium-setting type, and "SS" or slow-setting type. The "RS"type is subdivided into two categories having different viscosities,namely, "RS-1" and "RS-2."

Asphalt emulsions are prepared by dispersing molten asphalt in water inthe presence of an emulsifying agent, to form a cationic, anionic ornonionic emulsion, the character of the emulsion depending upon thenature of the emulsifying agent. The cationic and anionic emulsions aremuch more common than the nonionic emulsion.

Aggregate normally constitutes from about 90% to about 96% by weight ofasphalt-aggregate mixtures. The most commonly used aggregates are brokenstone and slag, crushed or uncrushed gravel, crushed limestone,disintegrated granite, sand and mineral filler. The type of asphalt andthe ultimate properties desired determine the type of aggregate to beemployed. Chemically, these aggregates can comprise calcium carbonate,calcium silicate, silicon dioxide and various iron, aluminum and othermineral-containing substances.

Further details on methods of combining aggregate and asphalt emulsionsand on proper proportions of the various sizes of aggregate for use indifferent construction applications may be found in a publication, TheAsphalt Handbook, Revised Edition, 1960, published by The AsphaltInstitute, College Park, Maryland.

In preparing the asphalt compositions of the invention, asphalt can bemixed with any of the common aggregates, such as crushed limestone,slag, crushed rock, sand, gravel, etc., to form an asphaltic concretefor paving. Silica-containing aggregates are however preferred. Thedesirable properties for such an asphalt cement may be found in highwayspecification manuals or in Abraham's text, Asphalt and AlliedSubstances. In general, asphalt cement for paving purposes is requiredto meet penetration specifications, and the preferred penetration willusually be from 50 to 200 at 77° F.

In preparing an asphaltic concrete for paving, the asphalt is mixed withaggregate in the proportion of from 4 to 10 parts by weight of asphaltto 96 to 90 parts by weight of aggregate at a temperature in the rangeof from 280° F. to 350° F., but preferably the temperature will beselected to give 120 seconds viscosity (Saybolt-Furol) for the asphaltcement employed.

The following Examples in the opinion of the inventors representpreferred embodiments of the invention.

EXAMPLE 1

To 200 g of asphalt solution (containing 170 g of petroleum residueasphalt dissolved in naphtha to form a solution there was added 3 g of3-decoxypropylamine. The resulting solution was then held for 1 day at130° C. in a sealed container. The container was then opened, and about9 g of the asphalt solution poured out on a sheet-metal disc having adiameter of 9 cm. The disc was held at 20° C., and after 30 minutes,twenty wet stones (granites from the Stockholm area, Sweden) size 8 to11 mm in diameter that had been washed in deionized water were presseddown into the asphalt layer. After another 30 minutes, the stones weretaken out, using a pair of tweezers, and were judged visually in respectof the surface area covered with asphalt, calculated in percent of thesurface area which had been in contact with the asphalt. The averagepercent surface area of the twenty stones represented the adhesion, andthe adhesion was found to be 97% by this test.

When the solution had been held for 2 days at 130° C., the adhesion wasfound to be 84%, and after 4 days at 130° C., the adhesion was found tobe 74%.

For comparison purposes, a similar composition was prepared using 200 gof the same asphalt solution but adding 3 g of dodecylamine. The asphaltsolution was stored at 130° C., and tested for adhesion to the stonesusing the same test procedure. After 1 day, 2 days and 4 days at thistemperature, the adhesion was found to be 76%, 70% and 59%,respectively. Thus, 3-decoxypropylamine showed considerably bettercapability for improving the adhesion of the asphalt to aggregate thandodecylamine.

EXAMPLES 2 to 5

Example 2 To 200 g of the same asphalt solution used in the tests ofExample 1, there were added 3 g of decoxypropylamine and 3 g ofmonoethanolamine. The asphalt solution was then stored at 130° C. for 24days. Samples of the composition were removed at 1 day, 2 days, 4 days,8 days, 12 days, 16 days, and 24 days, and tested for adhesion toaggregate using the test procedure outlined in Example 1. The resultsare reported in Table Ia).

Example 3 A similar composition was prepared using 3 g ofdecoxypropylamine and 3 g of diethanolamine, and these results are alsoreported in Table Ia).

Example 4 Similarly, asphalt compositions were prepared using 3 g of3-decoxypropylamine and 3 g of triethanolamine, and

Example 5: using 3 g of 3-decoxypropylamine and 3 g ofmonoisopropanolamine. The test results are reported in Table Ia).

For comparison purposes, the tests were run in parallel to an asphaltsolution containing 3 g of 3-decoxypropylamine but no alkanolamine, and3 g of dodecylamine but no alkanolamine. The results appear in TableIa).

For comparison purposes, the tests were also run in parallel to threeasphalt compositions each containing 3 g of one of the alkanolaminestested, and one asphalt composition containing no additive. The %adhesion in each case is given in Table Ib).

                  TABLE Ia).                                                      ______________________________________                                        Adhesion %                                                                    Ex.                                                                           No:  1       2        3     4     5      Control A                             Ether-Amine Additive:     Amine                                              3-decoxypropylamine plus   Additive:                                               No      Mono-    Di-   Tri-  Mono-                                       Days Alka-   etha-    etha- etha- Isopro-                                     at   nol-    nol-     nol-  nol-  panol- Dodecyl-                             130°                                                                        amine   amine    amine amine amine  amine                                ______________________________________                                         1   97      99       98    97    97     76                                    2   84      98       95    96    95     70                                    4   74      95       93    95    93     59                                    8   42      93       91    91    90     40                                   12   26      92       89    90    84     25                                   16   18      93       87    89    80     14                                   20   12      92       86    85    78      6                                   24    9      91       85    82    76     --                                   ______________________________________                                    

                  TABLE Ib).                                                      ______________________________________                                        Adhesion %                                                                    Controls: No ether amine   Control F                                          ______________________________________                                        1.5% Alkanolamine:                                                                   B        C        D      E                                             Days at                                                                              Mono-    Di       Tri-   Isopro-                                                                              No                                     130° C.                                                                       ethanol  ethanol  ethanol                                                                              panol  Amine                                  ______________________________________                                        1       --.sup.1                                                                              --       --     --     --                                     2      --       --       --     --     --                                     4      --       --       --     --     --                                     8      --       --       --     --     --                                     12     --       --       --     --     --                                     16     --       --       --     --     --                                     20     --       --       --     --     --                                     24     --       --       --     --     --                                     ______________________________________                                         .sup.1 The values obtained were in the range 0-5% which also is the           precision of the test method.                                            

The 3-decoxypropylamine gives a considerable improvement overdodecylamine.

The alkanolamine further improves the thermal stability of the asphaltsolutions containing 3-decoxypropylamine. The adhesion after 24 days at130° C. with each of the alkanolamines tested was superior not only tothat obtained using dodecylamine alone, but was still comparable to thatusing 3-decoxypropylamine alone after 2 to 4 days at the sametemperature. The alkanolamines alone were ineffective, and % adhesionwas equal to that obtained when no amine was present.

EXAMPLES 6 to 9

Example 6: To 200 g of the same asphalt solution used in the tests ofExample 1, there were added 3 g of decoxypropylamine. The asphaltsolution was then stored at 130° C. for 20 days. Samples of thecomposition were removed at 1 day, 2 days, 4 days, 8 days, 12 days, 16days, and 20 days, and tested for adhesion to aggregate, using the testprocedure outlined in Example 1. The results are reported in Table II.

Example 7: A similar composition was prepared, using 3 g ofdecoxypropylamine and 1 g of diethanolamine, and these results are alsoreported in Table II.

Example 8: Similarly, asphalt compositions were prepared using 3 g of3-decoxypropylamine and 2 g of diethanolamine, and

Example 9: using 3 g of 3-decoxypropylamine and 3 g of diethanolamine.The test results are reported in Table II.

                  TABLE II                                                        ______________________________________                                        Adhesion %                                                                    Example                                                                       No:     6        7        8      9      Control                               ______________________________________                                        Ether Amine Additive: 1.5% 3-decoxypropylamine plus                           Days    No       0.5% Di- 1.0% Di-                                                                             1.5% Di-                                     at      Alkanol- ethanol- ethanol-                                                                             ethanol-                                                                             No                                    130° C.                                                                        amine    amine    amine  amine  Additive                              ______________________________________                                        1       91       96       98     100     --.sup.1                             2       82       95       97     99     --                                    4       68       92       96     98     --                                    8       45       86       93     95     --                                    12      29       80       91     92     --                                    16      19       75       89     89     --                                    20      10       67       86     87     --                                    ______________________________________                                         .sup.1 The values obtained were in the range 0-5% which also is the           precision of the test method.                                            

The 3-decoxypropylamine gave good adhesion in this test compared to thecontrol.

The effect of the diethanolamine in further improving the thermalstability of the compositions with 3-decoxypropylamine is quiteremarkable. The adhesion after 20 days at 130° C. at 1% and 1.5%diethanolamine was superior to that obtained using 3-decoxypropylaminealone after two days at the same temperature.

EXAMPLES 10 to 12

Example 10: To 200 g of the same asphalt solution used in the tests ofExample 1, there were added 3 g of 3-octoxypropylamine. The asphaltsolution was then stored at 130° C. for 20 days. Samples of thecomposition were removed at 1 day, 2 days, 4 days, 8 days, 12 days, 16days, and 20 days, and tested for adhesion to aggregate, using the testprocedure outlined in Example 1. The results are reported in Table III.

Example 11: A similar composition was prepared using 3 g of3-octoxypropylamine and 3 g of monoethanolamine, and these results arealso reported in Table III.

Example 12. Similarly, an asphalt composition was prepared using 3 g of3-octoxypropylamine and 3 g of diethanolamine. The test results arereported in Table III.

                  TABLE III                                                       ______________________________________                                        Adhesion %                                                                    Example                                                                       No:     10       11          12      Control                                  ______________________________________                                        Ether Amine Additive: 1.5% 3-octoxypropylamine                                Days    No       1.5%        1.5%                                             at      Alkanol- Monoethanol-                                                                              Diethanol-                                                                            No                                       130° C.                                                                        amine    amine       amine   Additive                                 ______________________________________                                        1       85       99          93       --.sup.1                                2       85       99          93      --                                       4       83       98          93      --                                       8       75       97          92      --                                       12      61       96          89      --                                       16      40       95          86      --                                       20      13       94          81      --                                       ______________________________________                                         .sup.1 The values obtained were in the range 0-5% which also is the           precision of the test method.                                            

The 3-octoxypropylamine gave good adhesion in these tests, compared tothe control.

The alkanolamine further improved the thermal stability of the asphaltsolutions containing 3-octoxypropylamine. The adhesion after 20 days at130° C. in the case of monoethanolamine was superior to that obtainedusing 3-decoxypropylamine alone after two days at the same temperature.Diethanolamine gives results after 20 days comparable to3-decoxypropylamine alone after 5 days.

EXAMPLES 14 to 16

Example 14: To 200 g of the same asphalt solution used in the tests ofExample 1, there were added 3 g of 3-tetradecoxypropylamine. The asphaltsolution was then stored at 130° C. for 20 days. Samples of thecomposition were removed at 1 day, 2 days, 4 days, 8 days, 12 days, 16days, and 20 days, and tested for adhesion to aggregate, using the testprocedure outlined in Example 1. The results are reported in Table IV.

Example 15: A similar composition was prepared using 3 g or3-tetradecoxypropylamine and 3 g of monoethanolamine, and these resultsare also reported in Table IV.

Example 16: Similarly, an asphalt composition was prepared using 3 g of3-tetradecoxypropylamine and 3 g of diethanolamine. The test results arereported in Table IV.

                  TABLE IV                                                        ______________________________________                                        Adhesion %                                                                    Example                                                                       No:     14       15          16      Control                                  ______________________________________                                        Ether Amine Additive: 1.5% 3-tetradecoxypropylamine                           Days    No       1.5%        1.5%                                             at      Alkanol- Monoethanol-                                                                              Diethanol-                                                                            No                                       130° C.                                                                        amine    amine       amine   Additive                                 ______________________________________                                        1       74       99          94                                               2       62       99          94                                               4       43       97          93                                               8       18       95          92                                               12       5       93          89                                               16      --       90          85                                               20      --       88          80                                               ______________________________________                                         .sup.1 The values obtained were in the range 0-5% which also is the           precision of the test method.                                            

The 3-tetradecoxypropylamine gave good adhesion in this test, comparedto the control.

The alkanolamine further improved the thermal stability of the asphaltsolutions containing 3 -tetradecoxypropylamine. The adhesion after 20days at 130° C. in the case of each alkanolamine tested was superior tothat which is obtained using 3-decoxyproplamine alone after one day atthe same temperature.

EXAMPLES 17 to 19

Example 17: To 200 g of the same asphalt solution used in the tests ofExample 1, there were added 3 g of 3-(decoxydioxyethylene)oxypropylamine. The asphalt solution was then stored at 130° C. for 12days. Samples of the composition were removed at 1 day, 2 days, fourdays, 8 days, and 12 days, and tested for adhesion to aggregate, usingthe test procedure outlined in Example 1. The results are reported inTable V.

Example 18: A similar composition was prepared using 3 g of3-(decoxydioxyethylene) oxypropylamine and 3 g of monoethanolamine, andthese results are also reported in Table V.

Example 19: Similarly, an asphalt composition was prepared using 3 g of3-(decodydioxythylene) oxypropylamine and 3 g of diethanolamine. Thetest results are reported in Table V.

                  TABLE V                                                         ______________________________________                                        Adhesion %                                                                    Example                                                                       No:     17       18          19      Control                                  ______________________________________                                        Ether Amine Additive: 1.5% 3-(decoxydioxyethylene)-                           oxypropylamine                                                                Days    No       1.5%        1.5%                                             at      Alkanol- Monoethanol-                                                                              Diethanol-                                                                            No                                       130° C.                                                                        amine    amine       amine   Additive                                 ______________________________________                                        1       89       100         96                                               2       60       99          95                                               4       25       98          93                                               9        4       97          91                                               12      --       97          89                                               ______________________________________                                         .sup.1 The values obtained were in the range 0-5% which also is the           precision of the test method.                                            

The 3-(decoxydioxyethylene) oxypropylamine gave good adhesion in thistest compared to the control.

The alkanolamine further improved the thermal stability of the asphaltsolutions containing the ether amine. The adhesion after twelve days at130° C. in the case of each of the alkanolamines tested was equal orsuperior to that obtained using the ether amine alone, after one day atthe same temperature.

We claim:
 1. An additive for improving the adhesion of asphalt toaggregate comprising an ether amine having the general formula: ##STR6##wherein: R₁ is a hydrocarbon group having from about six to aboutsixteen carbon atoms, selected from the group consisting of alkyl andalkenyl;R₂, r₃, r₄ and R₅ are selected from the group consisting ofhydrogen and alkyl radicals having from one to about two carbon atoms;n₁ and n₂ are numbers within the range from one to about four; x₁ and x₂are numbers within the range from zero to about five, the sum of x₁ andx₂ being from one to five; the total number of carbon atoms in each##STR7## unit being from one to about four; and an alkanolamine havingthe formula: ##STR8## wherein: R₆ and R₇ are selected from the groupconsisting of hydrogen and alkyl groups having from one to about twocarbon atoms; n₃ is a number within the range from two to about four; x₃is a number within the range from one to about three; the total numberof carbon atoms in each ##STR9## unit being with the range from two tofour.
 2. An additive according to claim 1, in which the ether amine R₁is an alkyl group having from eight to about fourteen carbon atoms, thenumber of carbon atoms in each ##STR10## unit is two or three, x₁ isone, and x₂ is zero.
 3. An additive according to claim 1 in which thealkanolamine is an ethanolamine.